ABSTRACT
Rings or arcs of fungus-stimulated plant growth occur worldwide; these are commonly referred to as "fairy rings". In 2010, we discovered 2-azahypoxanthine (AHX), a compound responsible for the fairy-ring phenomenon caused by fungus; AHX stimulated the growth of all the plants tested. Herein, we reveal the isolation and structure determination of a common metabolite of AHX in plants, 2-aza-8-oxohypoxanthine (AOH). AHX is chemically synthesized from 5-aminoimidazole-4-carboxamide (AICA), and AHX can be converted into AOH by xanthine oxidase. AICA is one of the members of the purine metabolic pathway in animals, plants, and microorganisms. However, further metabolism of AICA remains elusive. Based on these results and facts, we hypothesized that plants themselves produce AHX and AOH through a pathway similar to the chemical synthesis. Herein, we demonstrate the existence of endogenous AHX and AOH and a novel purine pathway to produce them in plants.
Subject(s)
Hypoxanthines/metabolism , Oryza/metabolism , Purines/metabolism , Crystallography, X-Ray , Hypoxanthines/chemical synthesis , Hypoxanthines/chemistry , Molecular Conformation , Purines/chemistry , Xanthine Oxidase/metabolismABSTRACT
The chronological lifespan (CLS) of budding yeast is a model for the aging of post-mitotic cells in higher eukaryotes. We report here the development of a new method to assess yeast CLS. The new assay is simple, convenient and labor-saving. We applied this new method to screen natural compounds isolated from mushrooms and discovered beauveriolide I as a potent anti-aging agent.
Subject(s)
Agaricales/chemistry , Cellular Senescence/drug effects , Depsipeptides/pharmacology , High-Throughput Screening Assays , Saccharomyces cerevisiae/drug effects , Cellular Senescence/physiology , Cytochromes c1/deficiency , Cytochromes c1/genetics , Depsipeptides/chemistry , Depsipeptides/isolation & purification , Gene Expression , Histone Demethylases/deficiency , Histone Demethylases/genetics , Humans , Life Expectancy , Longevity , Mitosis/drug effects , Models, Biological , Phosphatidylinositol 3-Kinases/deficiency , Phosphatidylinositol 3-Kinases/genetics , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae Proteins/geneticsABSTRACT
Maturity group (based on the number of days to maturity) is an important growth trait for determining crop productivity, but there has been no attempt to examine the effects of elevated [CO(2)] on yield enhancement of rice cultivars with different maturity groups. Since early-maturing cultivars generally show higher plant N concentration than late-maturing cultivars, it is hypothesized that [CO(2)]-induced yield enhancement might be larger for early-maturing cultivars than late-maturing cultivars. To test this hypothesis, the effects of elevated [CO(2)] on yield components, biomass, N uptake, and leaf photosynthesis of cultivars with different maturity groups were examined for 2 years using a free-air CO(2) enrichment (FACE). Elevated [CO(2)] significantly increased grain yield and the magnitude significantly differed among the cultivars as detected by a significant [CO(2)] x cultivar interaction. Two cultivars (one with early and one with late maturity) responded more strongly to elevated [CO(2)] than those with intermediate maturity, resulting mainly from increases in spikelet density. Biomass and N uptake at the heading stage were closely correlated with grain yield and spikelet density over [CO(2)] and cultivars. Our 2 year field trial rejected the hypothesis that earlier cultivars would respond more to elevated [CO(2)] than later cultivars, but it is revealed that the magnitude of the growth enhancement before heading is a useful criterion for selecting rice cultivars capable of adapting to elevated [CO(2)].
